Glossary

dimension
dim: Fundamental, orthogonal directions associated available for constructing units.

For example mass, length, time.

In xo-unit these are represented by the enum xo::qty::dimension.
basis unit
bu: An implementation type representing a quantity (with associated scale) in the direction of a single dimension.

For example milliseconds, seconds, and hours stand for different basis units within the time dimension.

In xo-unit these are represented by the template type xo::qty::basis_unit.
basis power unit
bpu: A rational power of a (single) basis unit.

For example \(s^{-2}\) for unit “per second squared” or \(yr^{-(1/2)}\) for “per square-root of a year”.

In xo-unit these are represented by the template type xo::qty::bpu
natural unit
nu: A cartesian product of basis power units (bpus);

For example \(kg.m.s^{-2}\) or \(hr^{-(1/2)}\).

In xo-unit these are represented by template type xo::qty::natural_unit.
scaled unit
su: A dimensionless multiple of a natural unit.

Used as intermediate value when coalescing quantities involving different units.

In xo-unit these are represented by template type xo::qty::scaled_unit.
XO: A set of integrated c++ libraries for complex event processing, with browser and python integration. xo documentation here